Non-shorting wire cutter

ABSTRACT

A wire cutting device having a blade angle of about 0° and whose blades exhibit a bulk resistivity of at least about 1.0 ohm-cm can be used to safely sever plural conductors while in-service without causing a short circuit. Blade materials are typically polymeric materials with a Rockwell hardness of about M30 or greater.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to copending application of Siden,"Deformable Wire Stripper", Ser. No. 626,780 filed Oct. 29, 1975, whichis a continuation-in-part of copending application Ser. No. 480,821filed June 19, 1974, now U.S. Pat. No. 3,931,672 issued Jan. 13, 1976.The disclosures of these are incorporated by reference.

FIELD OF THE INVENTION

This invention relates to means for cutting wire. In another aspect itrelates to means for cutting plural individual conductors while inservice.

BACKGROUND OF THE INVENTION

Telephone cable is typically a package of plural individaul conductorshaving their own insulating sleeve or coating. This insulation normallyis a polymeric material. The individual insulated conductors (wires) arecombined into a bundle around which is disposed a covering layer ofrelatively heavy duty insulating material in order to provide protectionfrom mechanical damage, corrosion or other environmental hazards. Thuseach cable can carry numerous telephone "lines".

There are many instances when it is desirable to form a splice with theindividual wire members of a telephone cable to make a new circuit whenthe cable is in service in a manner that does not disturb that serviceand then detach one leg of the splice formed by the old cable. Thismight be done in order to replace a length of old cable or to makeconnection with new equipment.

Frequently these splices are made by what the art refers to as Y splicesusing specially adapted splice connectors of the MS² or SECS types.These provide means for making splices with the usual cable bundle of 50individual wire conductors to form the Y splice. Then one leg of the Yis detached without interrupting service. Heretofore, the practice hasbeen to detach the old circuit with conventional wire cutting equipment,typically metal snips or tool steel diagonal cutters. In order to dothis, the closely spaced wires must be carefully separated andindividually cut as near the splice connector as possible. Simultaneouscutting of multiple conductors is not possible because the metal toolwill cause a short circuit between one or more pairs of conductors anddisrupt service by causing the lines they carry to be non-usable or "gooff the air". Even when the wires are individually cut, accidentalcontact of the cutting tool with a previously cut wire can still resultin the short circuit condition. As a result, extreme care is demandedcausing the operation to be a very time consuming one.

Similar problems exist in other areas. For example, there are occasionswhen connection is made to a new computer before disconnection from theold in order to main continuous data processing or other service by thecomputers. If short circuits are caused in severing the old connectionsthat can cause service interruption.

From the foregoing, it can be seen that it would be a useful advance inthe art to provide a means for rapidly severing multiple conductors whenthey carry a current without causing a short circuit. Accordingly, oneobject of this invention is to provide an improved means for cutting orsevering plural conductors while they are in service.

Another object of this invention is to provide a process by which pluralconductors can be severed while in use.

SUMMARY OF THE INVENTION

The foregoing and other objects of this invention are achieved by theapparatus of the present invention in which cutting means are providedhaving a pair of blades that are offset from and movable relative toeach other so as to contact the substrate to be severed between them ata blade angle of about 0°. The blades should be of a material thatexhibits a bulk resistivity of at least about 1.0 ohm-cm. Preferably theblade material is an organic polymer having a Rockwell hardness of M30or greater.

Upon application of sufficient force to such blades and insulatedconductors located between them, the conductors can be severed withoutcausing a short circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of a pair of blades according to the presentinvention.

FIGS. 2 and 3 are illustrations of wire cutting devices of the presentinvention.

FIG. 4 illustrates a device adapted for use with splice connectors fortelephone cable.

FIGS. 5 and 6 are partial views in perspective of the device of FIG. 4as employed with a splice connector for telephone cable.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides a method and apparatus for cutting insulatedwires by which it is possible to cut plural insulated wiressimultaneously while the wires are carrying a current without creating ashort circuit between one or more pairs of the conductors. By use of theterm wire is meant not only conventional, concentrically arrangedinsulated conductors for which prior art wire cutters are normallydesigned to cut, but also, other "wire" configurations for which theinvention is particularly suited. Therefore, the term "wire" is not tobe narrowly construed as it includes a variety of conductor-insulationconfigurations of which flat cable and ribbon cable are also examples.

Referring now to FIG. 1, there is an illustration of a pair of blades 11and 12 having located there between a conventional wire 13 comprised ofa metal conductor 14 surrounded by an insulation cover 15.

It will be understood that the apparatus of the invention isparticularly useful for cutting multiple strands of conductor and thatonly one is shown merely for purposes of illustration.

Blades 11 and 12 are fabricated from a material having a bulkresistivity of at least about 1.0 ohm-cm in order that it not cause ashort circuit when the cutter is used to sever wires carrying a currentand in order that the severance of the wires can be made without dangerto the operator of the cutter. Surprisingly we have found that organicpolymers are particularly useful for this purpose even though theirhardness is considerably less than the conducting element of the wirebeing cut if the blades of the cutter are provided the configurationshown in FIG. 1.

As shown, blades 11 and 12 have a thickness of uniform cross-section,giving them a blade angle of 0°, in order that they will resistdeformation when contact is made with the wire 13 and conducting element14 after cutting through the insulation 15.

The blades are offset as shown in FIG. 1 in order to allow both bladesto pass through the wire from opposite sides. In FIG. 1, 16 and 17represent the opposing cutting edges by which wire is deformed and cut.The force required to deform the blade is large compared to the shearstrength of typical conductors. If the blades were designed as areconventional wire cutters, the blades of which are designed to passthrough the wire and contact each other on their cutting surfaces, theresult would be merely to compress the wire 13. Any displacement of theoffset blades should be as little as possible. Preferably it is lessthan 1 wire diameter.

In order to limit the blade thickness required to avoid deformation, theblade materials preferably have a Rockwell hardness of at least aboutM30. Suitable polymers for this purpose include thermoset resins andengineering thermoplastics such as epoxy resin, acrylic polymers such asthe homopolymers and copolymers of acrylic acid and similar acids suchas methacrylic acid and their alkyl esters such as ethyl acrylate andmethyl methacrylate, and acrylonitrile and its copolymers such asacrylonitrile-butadiene-styrene copolymer. Polyamides such as nylon 6/6,polycarbonates, and polyaromatic polymers such as polyphenylene oxide,polyaryl ketones, polyaryl sulfones and polystyrene can be used. Alsouseful are polyvinylidene fluoride, polyvinyl chloride and otherhaloolefin polymers. Formaldehyde resins such as acetals or thephenal-aldehyde resins would also be useful. The foregoing list it notan exhaustive one. Rather, it is merely illustrative of the types ofpolymers useful. These polymers in many cases can be advantageouslyemployed as reinforced or filled polymers where the reinforcement isglass or other inorganic fibers or particulates such as silica, aluminaand the like. Use of a blade fabricated from the polyaryl ketone Stilan(available from Raychem Corporation) of about 0.1 inches thick enablesone to cut conventional telephone wire of 18 to 22 awg copper oraluminum.

Blades 11 and 12 may be employed in a cutter where each moves relativeto the wire substrate. However, it is within the scope of the inventionfor one blade to be, in effect, an anvil and be fixed relative to thewire. Accordingly, the term "blade" includes an anvil structure.

The presently preferred embodiments of this invention are in the form ofhand held cutters in which the cutter 18 of FIG. 2 is illustrative.Cutter 18 is provided with handles 19 and 20 to move jaws 21 and 22,respectively, relative to each other about pivot member 23. Jaw 21 isprovided with a removable blade 24 having a blade angle of 0° fabricatedfrom a material as previously described. Jaw 22 is provided with blade25, also removably mounted, having a blade angle of 0°. As shown, theblades are offset relative to each other in order that they may passeach other but be in close proximity when moved into contact with andthrough the wire being cut.

A similar cutter is shown in FIG. 3 in which jaws 26 and 27 have blades28 and 29 respectively. Again the blades are removably mounted and a newblade can be used to displace the old when the latter is worn.

The effective cutting surface is determined by the cut width of the jawsand blades and, in the case of hand held cutters, can be as wide as willbe accommodated by the strength of the human hand or as narrow as theaccess requirements for specific purposes require.

In FIGS. 4-6 is shown a cutter specially adapted for use with SECS andMS² splice connectors used in splicing telephone cable. The upper jaw 30is provided with a blade 31 similar to the blades illustrated in FIGS. 2and 3. Both upper jaw 30 and lower jaw 32 are provided with slots 33 and34 to receive a splice connection 35 as shown in FIGS. 5 and 6. Only thedetails of connector 35 essential to the illustration of the presentinvention are shown. Shown in FIG. 5 are recesses 37, adapted to receivethe individual conductors of a telephone cable. Upper member 38 ispressed over the individual wires 39 and interlocks with lower member 40to securely retain the wires of the cable in the splice connector. Lowermember 40 is provided with plural means to pierce the insulation of theinsulated wires with a conducting element when the splice connector isassembled. These means are in electrical commmunication with theindividual wires (not shown) to be incorporated in the new circuit.

When jaws 30 and 32 are closed, a plurality of the wires of the oldcable can simultaneously be severed at the visible face of the spliceconnector (the extensions of these wires through the non-visible face ofthe splice connector are not shown) as shown in FIG. 6. In the assemblyshown in FIGS. 5 and 6, the surfaces of recesses 37 upon which the wires39 rest functions as one of the blades.

The use of the device of FIGS. 4-6 allow the wires to be cleanly cut atthe face of the connector quickly and without shorting. The methods ofthe prior art, such as using metal diagonal cutting pliers, requiredthat each member be cut individually. The cutters leave protrusions ofwire which, if the cutting is not done with great care, result inlengths of exposed wire which can still contact each other, if displacedwhile in service, to cause short-circuits.

The foregoing is a description of the presently preferred embodiments ofthe present invention. It will be apparent that modifications of thesecan be made without departure from the spirit and scope of theinvention. Accordingly, the present invention should be limited only bythe appended claims.

We claim:
 1. A non-shorting wire cutter comprising a pair of coactingblades having a blade angle of about 0°, said blades being offset fromeach other and at least one of said blades being movable relative to theother so that they pass each other as they move through a substrate fromopposite sides, said blades being fabricated from a material having abulk resistivity greater than about 1 ohm-cm and having sufficienthardness relative to their thickness to prevent substantial deformationwhen the blades are forced through the substrate.
 2. A wire cutteraccording to claim 1 wherein the blades have a Rockwell hardness ofabout M30 or greater.
 3. A wire cutter according to claim 1 wherein theblades are fabricated from an organic polymer.
 4. A wire cutteraccording to claim 3 wherein the organic polymer is selected from thegroup consisting of acrylic polymers, epoxy resins, acrylonitrile,acrylonitrile-butadiene-styrene copolymer, polycarbonates, polyarylketones, polyaryl sulfones, polystyrene, polyamides, acetals,phenolformaldehyde resins, and polymers of haloolefins.
 5. A wire cutteraccording to claim 4 wherein the polymer further comprises an inorganicfiller.
 6. A wire cutter according to claim 1 adapted for use with asplice connector for a wire substrate wherein one of the blades is asurface integral with the connector.
 7. A wire cutter according to claim1 wherein only one of the blades is movable relative to the other.
 8. Awire cutter according to claim 1 wherein both of the blades are movablerelative to the other.
 9. A process for simultaneously cutting pluralinsulated conductors without creating a short circuit comprisingdisposing said conductors between a pair of blade members having a bladeangle of about 0° and forcing the blades therethrough, said blades beingoffset from each other and at least one of which being movable relativeto the other, said blades being fabricated from a material having a bulkresistivity of at least about 1 ohm-cm and having sufficient hardnessrelative to their thickness to prevent substantial deformation when theblades are forced through the conductors.
 10. A process according toclaim 9 wherein the blades are fabricated from an organic polymer.
 11. Amethod according to claim 10 wherein the organic polymer is selectedfrom the group consisting of acrylic polymers, epoxy resins,acrylonitrile, acrylonitrile-butadiene-styrene copolymer,polycarbonates, polyaryl ketones, polyaryl sulfones, polystyrene,polyamides, acetals, phenolformaldehyde resins, and polymers ofhaloolefins.
 12. A method according to claim 11 wherein the polymerfurther comprises an inorganic filler.
 13. A non-shorting wire cuttingassembly comprising a blade having a blade angle of about 0°, connectormeans adapted to support a plurality of insulated conductors, means formoving at least one of said blade and said connector relative to theother through a path in which said blade and said connector are offsetfrom each other, said blade and said connector being fabricated from amaterial having a bulk resistivity greater than about 1 ohm-cm andhaving sufficient hardness relative to their thickness to preventsubstantial deformation when used to cut insulated wire.
 14. The wirecutting assembly of claim 13 wherein said blade and said connector arefabricated from an organic polymer.
 15. The wire cutting assembly ofclaim 14 wherein said surface of said connector adapted for supportinginsulated connectors has a blade angle of about 0°.